Selecting the duration of followup interviews is one of the most crucial choices researchers make in designing studies. The proper duration is a matter of controversy a followup duration that is too short may fail to detect late-appearing treatment effects, but na excessively long one would waste scarce resources and slow research progress. This project seeks to establish a firm quantitative foundation for followup design. Treatment has both short-term and long-term effects on drinking, and different factors seem to be associated with short-term and long-term success. Methods for separating these will be demonstrated, and methods for estimating long-term effects of treatment given shorter-term data will be developed and tested. Methods for projecting long-term health care use will also be developed and tested. The sensitivity of the methods and results obtained to differing criteria for treatment failure, and assumptions about missing data, will be determined. To achieve these primary goals, three-year followup data will be gathered on 380 patients from two ongoing studies: an ongoing patient-treatment matching study and the national multi-site alcohol treatment matching study. Under this project, patients who finish the followup protocols of their initial study will be recruited into extended followups extending three years from the beginning of treatment. To test the generalizability of the methods and results from the main samples, long-term outcome data from three independent studies will also be analyzed. This study will make several contributions to treatment science. First, it will generate information and methods for assessing the adequacy of followup designs and results. Second, it will demonstrate new techniques capable of detecting treatment effects that can be overlooked by existing methods. Third, it will provide ways of estimating long-term drinking outcome, which will permit presearchers to assess whether there is a potential for long-term effects from shorter-term data. Finally, it will extend our ability to assess the cost-effectiveness of alcohol treatment by providing methods to project long-term effects of treatment on health care utilization.